TRAIL OF ANNELID. 



373 



Some of the larger graptolites have been found at Granville, N. Y., within a mile or two of Vermont. 

 Without doubt they will be fuund within the State. E. Hitchcock, jr. states that there are specimens in 

 the slate of Williams and Tillson's quarry, in Fairhaven, very closely resembling fucoids and graptolites. 



FIG 256. 



Trail of aa Aunelid, Georgia. 



f 



Geological Position and Equivalency. 



Before presenting the different theories of the geological position and equivalency of 

 the Georgia slate, it will be necessary to state briefly the names and order of the groups 

 in Europe with which all our older rocks in America must be compared. The two oldest 

 groups of fossiliferous rocks in Europe are the Cambrian and the Lower or Cambro Silu- 

 rian. To the Cambrian group are referred the following rocks : the Longmyud rocks, in 

 "Wales, 26,000 feet thick, containing annelid tracks and a supposed trilobite, Palceopyge 

 Ramsayi ; rocks in Ireland, about Wicklow, containing tracks of articulata and small 

 zoophytes ; Skiddaw slate, in Cumberland, containing fossil plants ; in Bohemia, probably 

 Stage A (crystalline schist), and Stage B (slate and conglomerate) of M. Barrande. No 

 fossils known. In Scandinavia, Regio I, Fucoidarum of M. Angelin. If this group is 

 represented in this country, it is by the Huronian rocks of Canada, and some Azoic rocks 

 along the Apalachian ranges in the Middle and Southern States. 



The Lower Silurian rocks in Wales are the Lingula flags, the Llandeilo flags, the Cara- 

 doc sandstone and Bala beds, and the Lower Llandovery beds, which are 20,000 

 feet thick. In Cumberland the Coniston group of Professor Sedgwick is the equivalent 

 of the Caradoc sandstone of Wales. In Bohemia Stage C, "argillaceous schist," and 

 Stage D, quartzite, etc., of Barrande, are the representatives of the Lower Silurian. In 

 Scandinavia the Regiones A. olenorum, B. conocorypharum, BC. ceratopygarum, C. 

 asaphorum, and D. trinucleorum belong to this group. In this country the equivalency 

 of the rocks, described as Lower Silurian by Professor Hall, with these groups in Europe, 

 is satisfactory. These groups are all represented in Vermont, viz : from the Potsdam 

 sandstone to the Hudson River group, inclusive. 



